Valacyclovir halved transmission of genital herpes in study. (Controlled Trial of Antiviral in STD).

SAN DIEGO -- Once-daily valacyclovir halved transmission rates of herpes simplex virus 2 in the first randomized controlled trial to show that an antiviral medication can reduce the spread of a sexually transmitted disease.

The results address the "biggest fear" of couples in which one partner has genital herpes and the other doesn't--that they will give herpes or get it from their loved one, Dr. Lawrence Corey said at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy

The multicenter, 8-month study included 1,484 heterosexual, monogamous couples in which one partner had genital herpes simplex virus 2 (HSV-2) and the other partner was uninfected. Infected partners were randomized to once-daily treatment with 500-mg valacyclovir or placebo. GlaxosmithKline, which makes valacyclovir, funded the study

At monthly visits, investigators drew blood from the uninfected "susceptible" partners to test for HSV-2 antibodies; checked the infected "source" partners' adherence to therapy; collected sexual history diaries from all participants; and provided counseling advocating the use of condoms during sex.

Overall, 14(2%) of 743 susceptible partners in the valacyclovir group acquired symptomatic or asymptomatic HSV-2 infection, compared with 28 (4%) of 741 susceptible partners in the placebo group--a 50% reduction in the rate of transmission, said Dr. Corey, professor of medicine and laboratory medicine and head of the ...